Physicians have used elastic ligating bands to treat lesions, including internal hemorrhoids and mucositis and for performing mechanical hemostasis. The object of such ligation is to position a ligating band, which is usually elastic, over the targeted lesion or blood vessel section by first stretching the band beyond its undeformed diameter and then drawing the tissue to be ligated within the band. Thereafter the band is released so that it contracts, applying inward pressure on the section of tissue caught within the band. The effect of the inward pressure applied by the band is to stop all circulation through the targeted tissue, thereby causing the tissue to die. The body then sloughs off the dead tissue, or the dead tissue may be aspirated into an endoscope or a similar device.
Some previous ligating band dispensers allowed a user to dispense only a single ligating band at a time. That is, after a single ligating band was dispensed, if a user wanted to ligate another portion of tissue, the user would remove the device from the patient's body, load a new ligating band on the device and reinsert the device to the desired area within the patient's body.
U.S. Pat. No. 5,398,844 to Zaslavsky et al. (“the Zaslavsky '844 patent”), which is expressly incorporated by reference herein, describes a ligating band dispensing device including a substantially cylindrical support surface over which elastic ligating bands are stretched. The cylindrical support surface is typically attached to the distal end of an endoscope which is advanced into the body to a target area. A user then applies suction through the endoscope to draw the tissue to be ligated into the cylindrical support surface and releases a ligating band to contract around the tissue. While the device of the Zaslavsky '844 patent allows a user to place several ligating bands at desired locations without removing the device from the patient's body to reload ligating bands, it requires multiple pull strings to deploy the ligating bands. These pull strings may interfere with each other, may become tangled, or may take up excessive room in the endoscope working channel, thereby preventing the use of catheter-type accessory devices. In addition, as the number of ligating bands included on the distal end of these device is increased, the number of pull strings increases while the dispenser itself elongates. Accordingly, the field of vision from the endoscopes to which these devices are normally coupled has been correspondingly decreased.
U.S. Pat. No. 5,853,416 to Tolkoff (“the Tolkoff '416 patent”) and U.S. Pat. No. 6,059,798 (“the Tolkoff '798 patent”), both of which are expressly incorporated by reference herein, describe a distal end for a ligating band dispenser wherein a plurality of ligating bands can be actuated sequentially by the same trigger line. In addition, the bands can be located at a certain distance away from the distal end of the device, and all or part of the cylindrical support surface may be transparent for visualization.
U.S. Pat. No. 5,913,865 to Fortier et al. (“the Fortier '865 patent”), which is also expressly incorporated by reference herein, also describes a distal end for a ligating band dispenser that also allows a plurality of ligating bands to be actuated sequentially by the same trigger line. The supporting structure as shown in the embodiment of FIGS. 5–14 of the Fortier '865 patent includes a plurality of slots in the distal end of the device that are arranged so that the trigger line need only pass through each slot once. This helps prevent neighboring passes of the trigger line from becoming twisted or tangled with one another. In addition, the Fortier '865 patent describes that the slots can have alternating depths, such that alternating shallow slots and deeper slots are disposed on the distal end for retaining the trigger line. With such an arrangement, the lead part of the trigger line may be positioned in the shallower of two neighboring slots, thus insuring that the lead part of the trigger line is closer to the distal rim of the device. This increases deployment reliability. The deeper slot helps prevent the trigger line from coming off prematurely. In addition, each of the slots may be narrower than the trigger line, which also helps prevent the trigger line from prematurely exiting the slots.
As described in the Fortier '865 patent, and as shown in the embodiment of FIGS. 17–19 of that patent, the support surface also may include a plurality of axially extending ridges to assist in the deployment of the ligating bands by preventing the bands from sliding along the trigger line and facilitating rolling of the bands along the support surface. Having the bands roll, instead of slide, along the support surface promotes deployment of the bands. If a band slides along the support surface, it may not deploy. The axially extending ridges are described as having a frictional surface, which may include, for example, a plurality of transverse grooves or a sawtooth profile. (Col. 8, lines 2–4).
While the entire disclosure of the Fortier '865 patent is expressly incorporated by reference herein, specific reference is made to the embodiment of FIGS. 5–14 and the embodiment of FIGS. 17–19, as discussed above. Like the rest of the Fortier '865 patent, the description and illustration of these embodiments, including the means for deployment of the bands, is expressly incorporated herein by reference.
Physicians, when using a device such as one of the above-mentioned devices, often apply a lubricant to the device, to aid in intubation. While the lubricant aids in intubation, it also reduces the friction between the ligating bands and the support surface. The reduced friction may cause the ligating bands to slide instead of roll along the support surface, and hence may reduce the probability of a successful band deployment.